The invention relates to a trocar sleeve, comprising at its proximal side a housing, from the distal side of which a shaft projects, and with a sealing of elastic material in order to seal an instrument inserted into the trocar sleeve gas-tight into the proximal direction, wherein the sealing comprises a central opening, the diameter of which is variable, wherein the sealing comprises a position of rest in which the central opening comprises a smallest diameter, and comprising a spreading device which can be inserted into the sealing, extending same in doing so, whereby the diameter of the central opening can be enlarged.
Such a trocar sleeve is known from U.S. Pat. No. 5,209,737. The sealing consists herein of four flap-like sealing elements which surround a central opening. Spreading the sealing, wherein the diameter of the central opening is enlarged, is done by the instrument itself that is inserted into the trocar sleeve.
It is disadvantageous herein that the spreading force has to be applied by the inserted instrument or by the handling person, respectively, and, further, there is the danger that, when the instrument is removed, the flap-like sealing elements cock with the instrument, thus impeding the removal.
U.S. Pat. No. 5,458,640 discloses a cannula valve and seal system. The valve seal has a V-shaped cross section and includes two opposing lips which face each other across a slit. A tubular member is introduced into the valve seal for spreading the two opposing lips by moving the two lips laterally.
Trocars serve for effecting an incision into the body through which instruments can be introduced from the outer side into the body for the minimal-invasive surgery. A trocar consists of a trocar sleeve and, for setting the trocar, of a trocar arbor having a sharpened top in most cases. After setting the trocar, the trocar arbor is removed, and the trocar sleeve remains in the incision in the body. During minimal-invasive surgeries, different instruments are introduced through the trocar sleeve, e.g. endoscopes, medical forceps or other instruments provided with a long shaft. In this operation technique, it is further common to supply a gas into the body cavity in order to insufflate same. To this end, in most cases, a laterally projecting gas supply having a cock is provided in the region of the housing of the trocar sleeve.
As mentioned before, numerous different instruments are introduced or removed, respectively, through the trocar sleeve in the course of a minimal-invasive surgery.
In order to prevent gas from escaping from the body, either a flap valve is provided which automatically closes the trocar sleeve gas-tight versus the proximal direction, if no instrument is introduced into the sleeve, or a sealing is provided in the form of a slotted sealing, mostly at the transition between housing and shaft which can be pushed through and expanded by the instrument. It is true that this sealing can provide for a gas-tight seal, if no instrument is introduced, but due to the slotted geometry, a gas-tight seal is not possible with respect to the shaft of the introduced instrument having mostly a circle-round cross section.
For this reason, a sealing is provided in the trocar sleeve which comprises a central opening, the diameter of which corresponds approximately to the outer diameter of the shaft of the introduced instrument.
In other words, the sealing of elastic material comprises such an opening that the instrument can just be pushed through it and a gas-tight seal is nevertheless guaranteed.
As mentioned above, however, it is necessary that instruments having different shaft diameters can be introduced through the trocar sleeve.
If one takes a trocar sleeve having a clear inner diameter of 11 mm as an example, instruments having a shaft outer diameter of between 5 and 10 mm are usually introduced through the trocar sleeve.
If the sealing has an opening with a diameter of just 5 mm, an instrument having a shaft diameter of 6 mm could just be moved through the sealing by overcoming a resistance.
If, however, an instrument having a shaft diameter of 10 mm is to be introduced through this sealing, this is, if at all, only possible by applying a lot of force. Even if one should have succeeded in introducing an instrument having a shaft diameter of 10 mm through the opening having a size of 5 mm, it would be very disturbing and difficult for the operating person to move the instrument axially to-and-fro during the surgery. This will, at best, be performed in jerks, which is not desired.
It is an object of the present invention to improve a trocar sleeve having a sealing with a variable opening diameter in such a way that the enlarging process can be selectively performed and a safe sealing is guaranteed for different instrument diameters.